The present invention relates to an apparatus and a method for reducing and/or eliminating armature/needle bounce during operation.
During operation of High Pressure Direct Injection (HPDI) fuel injectors, armature/needle assembly closing action during the closing phase of the duty cycle is followed immediately by a secondary shorter reopen and closing phase called xe2x80x9cbouncexe2x80x9d. During this secondary reopen phase, additional, unwanted fuel is dispensed from the fuel injector. To improve high pressure fuel injector performance, the bounce must be minimized, or more preferably, eliminated.
One aspect of injector performance which has been addressed to reduce or eliminate bounce has been the flow of fuel through the armature. To solve the bounce problem, an anti-bounce orifice disk has been installed in the armature. The anti-bounce disk has a shape which provides a fuel path for fuel flow downstream toward the tip of the injector, but which obstructs fuel flow in the opposite, or upstream direction. Different anti-bounce orifice disks with different internal diameters are used to provide different flow rates. An anti-bounce orifice disk with a specific internal diameter is used to provide a desired flow rate. However, the specific internal diameter required is generally determined on a trial-and-error basis. This procedure requires different anti-bounce disks with different internal diameters which must be individually installed in and removed from the injector until the desired performance parameters of the injector are achieved. This process is time consuming and expensive.
It would be beneficial to provide an anti-bounce orifice disk with a single internal diameter that can be adjusted to provide different flow rates based on the axial position of the anti-bounce orifice disk within the armature/needle assembly, eliminating the costly insertion and removal of anti-bounce disks having different internal diameters.
An armature is provided. The armature comprises an upstream end, a downstream end and a longitudinal channel extending therethrough. The longitudinal channel includes an upstream portion having a first cross-sectional area and a downstream portion having a second cross-sectional area, with the second cross-sectional area being smaller than the first cross-sectional area. The downstream portion includes at least one interior wall. The armature further comprises a flow restrictor element inserted into the downstream portion of the longitudinal channel such that liquid flow from the downstream end to the upstream end is restricted.
An armature/needle assembly is provided. The assembly includes an armature and a needle. The armature comprises an upstream end, a downstream end and a longitudinal channel extending therethrough. The longitudinal channel includes an upstream portion having a first cross-sectional area and a downstream portion having a second cross-sectional area, with the second cross-sectional area being smaller than the first cross-sectional area. The downstream portion includes at least one interior wall. The armature further comprises a flow restrictor element inserted into the downstream portion of the longitudinal channel upstream of the at least one transverse channel such that liquid flow from the downstream end to the upstream end is restricted. The needle is located in the downstream portion of the longitudical channel such that the needle extends from the longitudinal channel.
A fuel injector is also provided. The fuel injector comprises an upstream end, a downstream end, a valve seat located at the downstream end, and an armature located between the upstream end and the downstream end. The armature includes an upstream armature end, a downstream armature end, and a longitudinal channel extending therethrough. The longitudinal channel includes an upstream portion having a first cross-sectional area and a downstream portion having a second cross-sectional area, with the second cross-sectional area being smaller than the first cross-sectional area. The downstream portion includes at least one interior wall. The armature further includes a flow restrictor element inserted into the downstream portion of the longitudinal channel such that liquid flow from the downstream armature end to the upstream armature end is restricted. The fuel injector further includes a needle located in the longitudinal channel downstream of the transverse channel, with the needle extending from the longitudinal channel. The needle is reciprocably engageable with the valve seat in a closed position.
A restrictor is provided. The restrictor comprises an upstream portion including at least a first leg and a second leg. Each of the first and second legs includes an upstream end and a downstream end. The upstream end of the first and second legs are connected by a transverse connector. The upstream portion further includes an upstream opening extending between the first and second legs. The restrictor further includes a downstream portion connected to the downstream end of each of the first and second legs. The downstream portion includes a generally central opening fluidly communicating with the upstream opening.
A method of reducing reverse fluid flow through an armature in a solenoid valve is provided. The method comprises providing an armature reciprocably located within the solenoid valve, the armature having an upstream end, a downstream end, and a channel extending therethrough; inserting a flow restrictor element into the channel, the flow restrictor element allowing flow from the upstream end toward the downstream end, but restricting flow from the downstream end toward the upstream end; and operating the solenoid valve.
A method of reducing bounce in an armature/needle assembly of a fuel injector is provided. The method comprises providing an armature reciprocably located within the fuel injector, the armature having an upstream end, a downstream end, and a channel extending therethrough; inserting a flow restrictor element into the channel, the flow restrictor element allowing flow from the upstream end toward the downstream end, but restricting flow from the downstream end toward the upstream end; and operating the fuel injector.
A method of setting a fuel flow rate in a fuel injector is provided. The method comprises: a) providing a fuel injector having an armature, the armature including an upstream end, a downstream end, and a channel extending therethrough; b) inserting a flow restrictor into the channel, the flow restrictor restricting fuel flow through the channel; c) operating the fuel injector; d) measuring a fuel flow rate through the fuel injector; e) adjusting a location of the flow restrictor in the channel; f) repeating steps c-e until a desired fuel flow rate is achieved; and g) securing the flow restrictor to the armature.